What gamehad Mij invented?

Mijinvented a game with a ping-pong ball,which kept him engrossed for up to half an hour at a time. Maxwellhad a suitcase that had become damaged, such that the lid, whenclosed, remained at a slope from one end to the other. Mij discoveredthat if the ball was placed on the high end, it would run down thelength of the suitcase. It would dash around to the other end tosurprise the ball. Then, it would grab it and trot off with it to thehigh end once more.